SQUID microscope read-out on a Josephson junction array

Abstract

LTC Josephson junction arrays (JJA) have recently gained interest as a model for the study of magnetization in superconductor materials. The presence of paramagnetic Meissner effect in such devices when field-cooled makes them an excellent candidate to discriminate between the different explanations given for such phenomenon. On the other hand, the understanding of the JJA physics is not simple due to the interplay between the non-linear behaviour of Josephson devices and the mutual induction effects in large JJA. The use of a SQUID microscope (SSM) to catch the magnetic image of the array is a distinctive feature of the experiment. So a study of SQUID read-out based on the actual JJA magnetic behaviour is needed in order to have a correct picture of what is going on. In this paper, using a simple way to reconstruct the complex array far-field viewed by the SQUID, we study how the flux read-out is dependent on array resolution, distance, tilting and noise for the typical situations in which arrays are found.

Magnetization of multiply connected superconductors with and without -junctions loops

“…For a large spread of areas (>20%), this further destroys the symmetry of the single loop solutions giving a larger interval of values of magnetization. This suggests that the off-sample far field magnetic image of the array [17] would result in a single Gaussian histogram as observed by Braunisch et al and others in [7].…”

“…interval of values of magnetization. This suggests that the off sample far field magnetic image of the array [17] would results in a single Gaussian histogram as observed by Braunisch et al [7].…”